Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 646 insertions, 0 deletions

diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
new file mode 100644
index 000000000..5c0216bd5
--- /dev/null
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -0,0 +1,646 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device operations for the pnfs nfs4 file layout driver.
+ *
+ * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
+ *
+ * Tao Peng <bergwolf@primarydata.com>
+ */
+
+#include <linux/nfs_fs.h>
+#include <linux/vmalloc.h>
+#include <linux/module.h>
+#include <linux/sunrpc/addr.h>
+
+#include "../internal.h"
+#include "../nfs4session.h"
+#include "flexfilelayout.h"
+
+#define NFSDBG_FACILITY		NFSDBG_PNFS_LD
+
+static unsigned int dataserver_timeo = NFS_DEF_TCP_TIMEO;
+static unsigned int dataserver_retrans;
+
+static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);
+
+void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
+{
+	if (!IS_ERR_OR_NULL(mirror_ds))
+		nfs4_put_deviceid_node(&mirror_ds->id_node);
+}
+
+void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
+{
+	nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
+	nfs4_pnfs_ds_put(mirror_ds->ds);
+	kfree(mirror_ds->ds_versions);
+	kfree_rcu(mirror_ds, id_node.rcu);
+}
+
+/* Decode opaque device data and construct new_ds using it */
+struct nfs4_ff_layout_ds *
+nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
+			    gfp_t gfp_flags)
+{
+	struct xdr_stream stream;
+	struct xdr_buf buf;
+	struct folio *scratch;
+	struct list_head dsaddrs;
+	struct nfs4_pnfs_ds_addr *da;
+	struct nfs4_ff_layout_ds *new_ds = NULL;
+	struct nfs4_ff_ds_version *ds_versions = NULL;
+	struct net *net = server->nfs_client->cl_net;
+	u32 mp_count;
+	u32 version_count;
+	__be32 *p;
+	int i, ret = -ENOMEM;
+
+	/* set up xdr stream */
+	scratch = folio_alloc(gfp_flags, 0);
+	if (!scratch)
+		goto out_err;
+
+	new_ds = kzalloc_obj(struct nfs4_ff_layout_ds, gfp_flags);
+	if (!new_ds)
+		goto out_scratch;
+
+	nfs4_init_deviceid_node(&new_ds->id_node,
+				server,
+				&pdev->dev_id);
+	INIT_LIST_HEAD(&dsaddrs);
+
+	xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
+	xdr_set_scratch_folio(&stream, scratch);
+
+	/* multipath count */
+	p = xdr_inline_decode(&stream, 4);
+	if (unlikely(!p))
+		goto out_err_drain_dsaddrs;
+	mp_count = be32_to_cpup(p);
+	dprintk("%s: multipath ds count %d\n", __func__, mp_count);
+
+	for (i = 0; i < mp_count; i++) {
+		/* multipath ds */
+		da = nfs4_decode_mp_ds_addr(net, &stream, gfp_flags);
+		if (da)
+			list_add_tail(&da->da_node, &dsaddrs);
+	}
+	if (list_empty(&dsaddrs)) {
+		dprintk("%s: no suitable DS addresses found\n",
+			__func__);
+		ret = -ENOMEDIUM;
+		goto out_err_drain_dsaddrs;
+	}
+
+	/* version count */
+	p = xdr_inline_decode(&stream, 4);
+	if (unlikely(!p))
+		goto out_err_drain_dsaddrs;
+	version_count = be32_to_cpup(p);
+
+	if (version_count == 0) {
+		ret = -EINVAL;
+		goto out_err_drain_dsaddrs;
+	}
+	dprintk("%s: version count %d\n", __func__, version_count);
+
+	ds_versions = kzalloc_objs(struct nfs4_ff_ds_version, version_count,
+				   gfp_flags);
+	if (!ds_versions)
+		goto out_err_drain_dsaddrs;
+
+	for (i = 0; i < version_count; i++) {
+		/* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
+		 * tightly_coupled(4) */
+		p = xdr_inline_decode(&stream, 20);
+		if (unlikely(!p))
+			goto out_err_drain_dsaddrs;
+		ds_versions[i].version = be32_to_cpup(p++);
+		ds_versions[i].minor_version = be32_to_cpup(p++);
+		ds_versions[i].rsize = nfs_io_size(be32_to_cpup(p++),
+						   server->nfs_client->cl_proto);
+		ds_versions[i].wsize = nfs_io_size(be32_to_cpup(p++),
+						   server->nfs_client->cl_proto);
+		ds_versions[i].tightly_coupled = be32_to_cpup(p);
+
+		if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
+			ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
+		if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
+			ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;
+
+		/*
+		 * check for valid major/minor combination.
+		 * currently we support dataserver which talk:
+		 *   v3, v4.0, v4.1, v4.2
+		 */
+		if (!((ds_versions[i].version == 3 && ds_versions[i].minor_version == 0) ||
+			(ds_versions[i].version == 4 && ds_versions[i].minor_version < 3))) {
+			dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
+				i, ds_versions[i].version,
+				ds_versions[i].minor_version);
+			ret = -EPROTONOSUPPORT;
+			goto out_err_drain_dsaddrs;
+		}
+
+		dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
+			__func__, i, ds_versions[i].version,
+			ds_versions[i].minor_version,
+			ds_versions[i].rsize,
+			ds_versions[i].wsize,
+			ds_versions[i].tightly_coupled);
+	}
+
+	new_ds->ds_versions = ds_versions;
+	new_ds->ds_versions_cnt = version_count;
+
+	new_ds->ds = nfs4_pnfs_ds_add(net, &dsaddrs, ds_versions[0].version,
+				      gfp_flags);
+	if (!new_ds->ds)
+		goto out_err_drain_dsaddrs;
+
+	/* If DS was already in cache, free ds addrs */
+	while (!list_empty(&dsaddrs)) {
+		da = list_first_entry(&dsaddrs,
+				      struct nfs4_pnfs_ds_addr,
+				      da_node);
+		list_del_init(&da->da_node);
+		kfree(da->da_remotestr);
+		kfree(da);
+	}
+
+	folio_put(scratch);
+	return new_ds;
+
+out_err_drain_dsaddrs:
+	while (!list_empty(&dsaddrs)) {
+		da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
+				      da_node);
+		list_del_init(&da->da_node);
+		kfree(da->da_remotestr);
+		kfree(da);
+	}
+
+	kfree(ds_versions);
+out_scratch:
+	folio_put(scratch);
+out_err:
+	kfree(new_ds);
+
+	dprintk("%s ERROR: returning %d\n", __func__, ret);
+	return NULL;
+}
+
+static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
+			    u64 offset, u64 length)
+{
+	u64 end;
+
+	end = max_t(u64, pnfs_end_offset(err->offset, err->length),
+		    pnfs_end_offset(offset, length));
+	err->offset = min_t(u64, err->offset, offset);
+	err->length = end - err->offset;
+}
+
+static int
+ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1,
+		const struct nfs4_ff_layout_ds_err *e2)
+{
+	int ret;
+
+	if (e1->opnum != e2->opnum)
+		return e1->opnum < e2->opnum ? -1 : 1;
+	if (e1->status != e2->status)
+		return e1->status < e2->status ? -1 : 1;
+	ret = memcmp(e1->stateid.data, e2->stateid.data,
+			sizeof(e1->stateid.data));
+	if (ret != 0)
+		return ret;
+	ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid));
+	if (ret != 0)
+		return ret;
+	if (pnfs_end_offset(e1->offset, e1->length) < e2->offset)
+		return -1;
+	if (e1->offset > pnfs_end_offset(e2->offset, e2->length))
+		return 1;
+	/* If ranges overlap or are contiguous, they are the same */
+	return 0;
+}
+
+static void
+ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
+			      struct nfs4_ff_layout_ds_err *dserr)
+{
+	struct nfs4_ff_layout_ds_err *err, *tmp;
+	struct list_head *head = &flo->error_list;
+	int match;
+
+	/* Do insertion sort w/ merges */
+	list_for_each_entry_safe(err, tmp, &flo->error_list, list) {
+		match = ff_ds_error_match(err, dserr);
+		if (match < 0)
+			continue;
+		if (match > 0) {
+			/* Add entry "dserr" _before_ entry "err" */
+			head = &err->list;
+			break;
+		}
+		/* Entries match, so merge "err" into "dserr" */
+		extend_ds_error(dserr, err->offset, err->length);
+		list_replace(&err->list, &dserr->list);
+		kfree(err);
+		return;
+	}
+
+	list_add_tail(&dserr->list, head);
+}
+
+int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
+			     struct nfs4_ff_layout_mirror *mirror,
+			     u32 dss_id, u64 offset, u64 length, int status,
+			     enum nfs_opnum4 opnum, gfp_t gfp_flags)
+{
+	struct nfs4_ff_layout_ds_err *dserr;
+
+	if (status == 0)
+		return 0;
+
+	if (IS_ERR_OR_NULL(mirror->dss[dss_id].mirror_ds))
+		return -EINVAL;
+
+	dserr = kmalloc_obj(*dserr, gfp_flags);
+	if (!dserr)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&dserr->list);
+	dserr->offset = offset;
+	dserr->length = length;
+	dserr->status = status;
+	dserr->opnum = opnum;
+	nfs4_stateid_copy(&dserr->stateid, &mirror->dss[dss_id].stateid);
+	memcpy(&dserr->deviceid, &mirror->dss[dss_id].mirror_ds->id_node.deviceid,
+	       NFS4_DEVICEID4_SIZE);
+
+	spin_lock(&flo->generic_hdr.plh_inode->i_lock);
+	ff_layout_add_ds_error_locked(flo, dserr);
+	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
+	return 0;
+}
+
+static const struct cred *
+ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode, u32 dss_id)
+{
+	const struct cred *cred, __rcu **pcred;
+
+	if (iomode == IOMODE_READ)
+		pcred = &mirror->dss[dss_id].ro_cred;
+	else
+		pcred = &mirror->dss[dss_id].rw_cred;
+
+	rcu_read_lock();
+	do {
+		cred = rcu_dereference(*pcred);
+		if (!cred)
+			break;
+
+		cred = get_cred_rcu(cred);
+	} while(!cred);
+	rcu_read_unlock();
+	return cred;
+}
+
+struct nfs_fh *
+nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror, u32 dss_id)
+{
+	/* FIXME: For now assume there is only 1 version available for the DS */
+	return &mirror->dss[dss_id].fh_versions[0];
+}
+
+void
+nfs4_ff_layout_select_ds_stateid(const struct nfs4_ff_layout_mirror *mirror,
+				 u32 dss_id,
+				 nfs4_stateid *stateid)
+{
+	if (nfs4_ff_layout_ds_version(mirror, dss_id) == 4)
+		nfs4_stateid_copy(stateid, &mirror->dss[dss_id].stateid);
+}
+
+static bool
+ff_layout_init_mirror_ds(struct pnfs_layout_hdr *lo,
+			 struct nfs4_ff_layout_mirror *mirror,
+			 u32 dss_id)
+{
+	if (mirror == NULL)
+		goto outerr;
+	if (mirror->dss[dss_id].mirror_ds == NULL) {
+		struct nfs4_deviceid_node *node;
+		struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV);
+
+		node = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode),
+				&mirror->dss[dss_id].devid, lo->plh_lc_cred,
+				GFP_KERNEL);
+		if (node)
+			mirror_ds = FF_LAYOUT_MIRROR_DS(node);
+
+		/* check for race with another call to this function */
+		if (cmpxchg(&mirror->dss[dss_id].mirror_ds, NULL, mirror_ds) &&
+		    mirror_ds != ERR_PTR(-ENODEV))
+			nfs4_put_deviceid_node(node);
+	}
+
+	if (IS_ERR(mirror->dss[dss_id].mirror_ds))
+		goto outerr;
+
+	return true;
+outerr:
+	return false;
+}
+
+/**
+ * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call
+ * @lseg: the layout segment we're operating on
+ * @mirror: layout mirror describing the DS to use
+ * @dss_id: DS stripe id to select stripe to use
+ * @fail_return: return layout on connect failure?
+ *
+ * Try to prepare a DS connection to accept an RPC call. This involves
+ * selecting a mirror to use and connecting the client to it if it's not
+ * already connected.
+ *
+ * Since we only need a single functioning mirror to satisfy a read, we don't
+ * want to return the layout if there is one. For writes though, any down
+ * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish
+ * between the two cases.
+ *
+ * Returns a pointer to a connected DS object on success or NULL on failure.
+ */
+struct nfs4_pnfs_ds *
+nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
+			  struct nfs4_ff_layout_mirror *mirror,
+			  u32 dss_id,
+			  bool fail_return)
+{
+	struct nfs4_pnfs_ds *ds;
+	struct inode *ino = lseg->pls_layout->plh_inode;
+	struct nfs_server *s = NFS_SERVER(ino);
+	unsigned int max_payload;
+	int status = -EAGAIN;
+
+	if (!ff_layout_init_mirror_ds(lseg->pls_layout, mirror, dss_id))
+		goto noconnect;
+
+	ds = mirror->dss[dss_id].mirror_ds->ds;
+	if (READ_ONCE(ds->ds_clp))
+		goto out;
+	/* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
+	smp_rmb();
+
+	/* FIXME: For now we assume the server sent only one version of NFS
+	 * to use for the DS.
+	 */
+	status = nfs4_pnfs_ds_connect(s, ds, &mirror->dss[dss_id].mirror_ds->id_node,
+			     dataserver_timeo, dataserver_retrans,
+			     mirror->dss[dss_id].mirror_ds->ds_versions[0].version,
+			     mirror->dss[dss_id].mirror_ds->ds_versions[0].minor_version,
+			     mirror->dss[dss_id].mirror_ds->ds_versions[0].tightly_coupled);
+
+	/* connect success, check rsize/wsize limit */
+	if (!status) {
+		/*
+		 * ds_clp is put in destroy_ds().
+		 * keep ds_clp even if DS is local, so that if local IO cannot
+		 * proceed somehow, we can fall back to NFS whenever we want.
+		 */
+		nfs_local_probe_async(ds->ds_clp);
+		max_payload =
+			nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
+				       NULL);
+		if (mirror->dss[dss_id].mirror_ds->ds_versions[0].rsize > max_payload)
+			mirror->dss[dss_id].mirror_ds->ds_versions[0].rsize = max_payload;
+		if (mirror->dss[dss_id].mirror_ds->ds_versions[0].wsize > max_payload)
+			mirror->dss[dss_id].mirror_ds->ds_versions[0].wsize = max_payload;
+		goto out;
+	}
+noconnect:
+	ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
+				 mirror, dss_id, lseg->pls_range.offset,
+				 lseg->pls_range.length, NFS4ERR_NXIO,
+				 OP_ILLEGAL, GFP_NOIO);
+	ff_layout_send_layouterror(lseg);
+	if (fail_return || !ff_layout_has_available_ds(lseg))
+		pnfs_error_mark_layout_for_return(ino, lseg);
+	ds = ERR_PTR(status);
+out:
+	return ds;
+}
+
+const struct cred *
+ff_layout_get_ds_cred(struct nfs4_ff_layout_mirror *mirror,
+		      const struct pnfs_layout_range *range,
+		      const struct cred *mdscred,
+		      u32 dss_id)
+{
+	const struct cred *cred;
+
+	if (mirror && !mirror->dss[dss_id].mirror_ds->ds_versions[0].tightly_coupled) {
+		cred = ff_layout_get_mirror_cred(mirror, range->iomode, dss_id);
+		if (!cred)
+			cred = get_cred(mdscred);
+	} else {
+		cred = get_cred(mdscred);
+	}
+	return cred;
+}
+
+/**
+ * nfs4_ff_find_or_create_ds_client - Find or create a DS rpc client
+ * @mirror: pointer to the mirror
+ * @ds_clp: nfs_client for the DS
+ * @inode: pointer to inode
+ * @dss_id: DS stripe id
+ *
+ * Find or create a DS rpc client with th MDS server rpc client auth flavor
+ * in the nfs_client cl_ds_clients list.
+ */
+struct rpc_clnt *
+nfs4_ff_find_or_create_ds_client(struct nfs4_ff_layout_mirror *mirror,
+				 struct nfs_client *ds_clp, struct inode *inode,
+				 u32 dss_id)
+{
+	switch (mirror->dss[dss_id].mirror_ds->ds_versions[0].version) {
+	case 3:
+		/* For NFSv3 DS, flavor is set when creating DS connections */
+		return ds_clp->cl_rpcclient;
+	case 4:
+		return nfs4_find_or_create_ds_client(ds_clp, inode);
+	default:
+		BUG();
+	}
+}
+
+void ff_layout_free_ds_ioerr(struct list_head *head)
+{
+	struct nfs4_ff_layout_ds_err *err;
+
+	while (!list_empty(head)) {
+		err = list_first_entry(head,
+				struct nfs4_ff_layout_ds_err,
+				list);
+		list_del(&err->list);
+		kfree(err);
+	}
+}
+
+/* called with inode i_lock held */
+int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head)
+{
+	struct nfs4_ff_layout_ds_err *err;
+	__be32 *p;
+
+	list_for_each_entry(err, head, list) {
+		/* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
+		 * + array length + deviceid(NFS4_DEVICEID4_SIZE)
+		 * + status(4) + opnum(4)
+		 */
+		p = xdr_reserve_space(xdr,
+				28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
+		if (unlikely(!p))
+			return -ENOBUFS;
+		p = xdr_encode_hyper(p, err->offset);
+		p = xdr_encode_hyper(p, err->length);
+		p = xdr_encode_opaque_fixed(p, &err->stateid,
+					    NFS4_STATEID_SIZE);
+		/* Encode 1 error */
+		*p++ = cpu_to_be32(1);
+		p = xdr_encode_opaque_fixed(p, &err->deviceid,
+					    NFS4_DEVICEID4_SIZE);
+		*p++ = cpu_to_be32(err->status);
+		*p++ = cpu_to_be32(err->opnum);
+		dprintk("%s: offset %llu length %llu status %d op %d\n",
+			__func__, err->offset, err->length, err->status,
+			err->opnum);
+	}
+
+	return 0;
+}
+
+static
+unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
+				      const struct pnfs_layout_range *range,
+				      struct list_head *head,
+				      unsigned int maxnum)
+{
+	struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo);
+	struct inode *inode = lo->plh_inode;
+	struct nfs4_ff_layout_ds_err *err, *n;
+	unsigned int ret = 0;
+
+	spin_lock(&inode->i_lock);
+	list_for_each_entry_safe(err, n, &flo->error_list, list) {
+		if (!pnfs_is_range_intersecting(err->offset,
+				pnfs_end_offset(err->offset, err->length),
+				range->offset,
+				pnfs_end_offset(range->offset, range->length)))
+			continue;
+		if (!maxnum)
+			break;
+		list_move(&err->list, head);
+		maxnum--;
+		ret++;
+	}
+	spin_unlock(&inode->i_lock);
+	return ret;
+}
+
+unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
+				      const struct pnfs_layout_range *range,
+				      struct list_head *head,
+				      unsigned int maxnum)
+{
+	unsigned int ret;
+
+	ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum);
+	/* If we're over the max, discard all remaining entries */
+	if (ret == maxnum) {
+		LIST_HEAD(discard);
+		do_layout_fetch_ds_ioerr(lo, range, &discard, -1);
+		ff_layout_free_ds_ioerr(&discard);
+	}
+	return ret;
+}
+
+static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg)
+{
+	struct nfs4_ff_layout_mirror *mirror;
+	struct nfs4_deviceid_node *devid;
+	u32 idx, dss_id;
+
+	for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
+		mirror = FF_LAYOUT_COMP(lseg, idx);
+		if (!mirror)
+			continue;
+		for (dss_id = 0; dss_id < mirror->dss_count; dss_id++) {
+			if (!mirror->dss[dss_id].mirror_ds)
+				return true;
+			if (IS_ERR(mirror->dss[dss_id].mirror_ds))
+				continue;
+			devid = &mirror->dss[dss_id].mirror_ds->id_node;
+			if (!nfs4_test_deviceid_unavailable(devid))
+				return true;
+		}
+	}
+
+	return false;
+}
+
+static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
+{
+	struct nfs4_ff_layout_mirror *mirror;
+	struct nfs4_deviceid_node *devid;
+	u32 idx, dss_id;
+
+	for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
+		mirror = FF_LAYOUT_COMP(lseg, idx);
+		if (!mirror)
+			return false;
+		for (dss_id = 0; dss_id < mirror->dss_count; dss_id++) {
+			if (IS_ERR(mirror->dss[dss_id].mirror_ds))
+				return false;
+			if (!mirror->dss[dss_id].mirror_ds)
+				continue;
+			devid = &mirror->dss[dss_id].mirror_ds->id_node;
+			if (nfs4_test_deviceid_unavailable(devid))
+				return false;
+		}
+	}
+
+	return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
+}
+
+static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
+{
+	if (lseg->pls_range.iomode == IOMODE_READ)
+		return  ff_read_layout_has_available_ds(lseg);
+	/* Note: RW layout needs all mirrors available */
+	return ff_rw_layout_has_available_ds(lseg);
+}
+
+bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg)
+{
+	return ff_layout_no_fallback_to_mds(lseg) ||
+	       ff_layout_has_available_ds(lseg);
+}
+
+bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg)
+{
+	return lseg->pls_range.iomode == IOMODE_RW &&
+	       ff_layout_no_read_on_rw(lseg);
+}
+
+module_param(dataserver_retrans, uint, 0644);
+MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
+			"retries a request before it attempts further "
+			" recovery  action.");
+module_param(dataserver_timeo, uint, 0644);
+MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
+			"NFSv4.1  client  waits for a response from a "
+			" data server before it retries an NFS request.");